Magnetic tunnel junction (mtj) fabrication methods and systems

ABSTRACT

Embodiments of the present invention facilitate efficient and effective increased memory cell density configuration. In one embodiment, the method comprises: forming a first pitch reference component and a second pitch reference component; forming a first pillar magnetic tunnel junction (pMTJ) located in a first level and a second pMTJ located in a second level, wherein the location of the second pMTJ with respect to the first pMTJ is coordinated based upon a reference pitch distance between the first pitch reference component and first pitch reference component. In one exemplary implementation, the first pitch reference component is a first switch coupled to the first pMTJ and the second pitch reference component is a second switch coupled to the second pMTJ. The reference component size can be based upon a minimum lithographic processing dimension.

FIELD OF THE INVENTION

The present invention relates to the field of memory device structurefabrication.

BACKGROUND OF THE INVENTION

Electronic systems and devices have made a significant contributiontowards the advancement of modern society and have facilitated increasedproductivity and reduced costs in analyzing and communicatinginformation in a variety of business, science, education, andentertainment applications. These electronic systems and devicestypically include information storage capabilities. Ever greater desireand market pressure for more storage capabilities in smaller devicescreates a demand for increased storage component densities. However, asa practical matter there a number of issues (e.g., fabricationconsiderations, photolithograph capabilities, electrical interferencebetween components, etc.) that limit conventional device componentdensities.

Some memory devices include storage components that operate based uponelectromagnetic principles. Magnetic memory devices typically storeinformation by adjusting and holding magnetic fields within componentsof the device. Stored information (e.g., bits, logical ones and zeros,true/false indications, etc.) corresponds to a state of the magneticfields and resulting electrically resistive characteristics. A memorycell that includes a magnetic tunnel junction (MTJ) is one type ofmagnetic memory structure. A MTJ typically includes ferromagneticportions separated by a non-magnetic material. The magnetic orientationor spin of a ferromagnetic portion can be altered and results in achange to the electrical resistive characteristics of the device. Thechange in resistive characteristics can have different impacts on anelectric current passing through the structure. The state orcharacteristics of the current are associated with indications of thestored information.

Limitations on lithographic processes used to create a MTJ are usuallythe deciding factor in dictating the pitch or distance between memorycells. Given resolution limitations of conventional lithographicprocesses, the resulting relatively large pitch between conventional MTJmemory cells leads to corresponding limits on traditional densitycompaction. A MTJ typically has a circular configuration and is referredto as a pillar MTJ (pMTJ). Conventional lithography tools currently cantypically print MTJ circles or pillars down to sizes of approximately 70nm in diameter with 20 nm separation between adjacent MTJs. This resultsin a conventional pitch of about 90 nm. The size of a traditional MTJcan optionally be trimmed down (e.g., to 20 or 30 nm) to make smallerpillars. However, due to the initial lithographic process placement orseparation of the pMTJ (e.g., 90 nm) the density remains substantiallythe same as the initial pitch limitation even if the MTJ is trimmed.While trimming down from the initial size to a smaller final size mayenable improved current or voltage characteristic, trimmingtraditionally does not help increase density. Thus, traditional memorycell pitch and density improvement is typically limited by lithographycapabilities

SUMMARY

Embodiments of the present invention facilitate efficient and effectiveincreased memory cell density configuration. In one embodiment, amagnetic memory fabrication method comprises: forming a first pitchreference component; forming a second pitch reference component; forminga first pillar magnetic tunnel junction (pMTJ) located in a first levelin the semiconductor device using a first run lithographic process;forming a second pillar magnetic tunnel junction (pMTJ) located in asecond level in the semiconductor device using a second run lithographicprocess, wherein the location of the second pMTJ with respect to thefirst pMTJ is coordinated based upon a reference pitch distance betweenthe first pitch reference component and first pitch reference component.In one exemplary implementation, the first pitch reference component isa first switch coupled to the first pMTJ and the second pitch referencecomponent is a second switch coupled to the second pMTJ. The referencecomponent size can be based upon a minimum lithographic processingdimension. A minimum lithographic processing dimension associated withthe first pitch reference component and the second pitch referencecomponent is less than a minimum lithographic processing dimensionassociated with the first pMTJ and the second pMTJ. The smallestdimension can correspond to a conductive line trace. The pMTJ can beformed using a hard mask and ion beam etch.

The reference component size can be based upon a minimum trimmingprocessing dimension. The first pMTJ and the second pMTJ can also betrimmed. In one exemplary implementation, the first pitch referencecomponent is a first switch coupled to the first pMTJ and the secondpitch reference component is a second switch coupled to the second pMTJ.The pMTJs can be formed using a hard mask and ion beam etch. The firstswitch and second switches can be transistors.

In one embodiment, a memory cell fabrication method comprises: forming afirst pMTJ located in a first level in the semiconductor device, whereinthe first pMTJ is associated with a first memory cell; and forming asecond pMTJ located in a second level in the semiconductor device,wherein the second pMTJ is associated with a second memory cell, whereinthe location of the second pMTJ with respect to the first pMTJ iscoordinated to comply with a reference pitch. In one exemplaryimplementation, the method further comprises: forming a first pitchreference component, wherein the first pitch reference component isassociated with the first pillar magnetic tunnel junction (pMTJ) memorycell; and forming a second pitch reference component, wherein the secondpitch reference component is associated with the first pMTJ memory cell,wherein a pitch between the first pitch reference component and thesecond pitch reference component is used to determine the referencepitch. In one exemplary implementation, fabrication processes utilizedto form the first pitch reference component and the second pitchreference have a greater resolution than fabrication processes utilizedto form the first pMTJ and second pMTJ. A portion of the second pMTJoverlaps a portion of the first pMTJ and the overlap is coordinated tocomply with a reference pitch associated with other components and anoffset in pattern difference between the first level and the secondlevel corresponds to the offset. A first lithographic mask can beutilized to form the first pMTJ and a second lithographic mask can beutilized to form the second pMTJ, wherein lithographic patterns forforming the first pMTJ and second pMTJ are the same except they areoffset from one another to correspond to the overlap. In one embodiment,lithographic printing capabilities with respect to the first pitchreference component and the second pitch reference component are used toset the reference pitch.

In one embodiment, a memory cell array formation method comprises:forming a first memory cell with a first magnetic tunnel junction (MTJ)located in a first level, forming a second memory cell with a secondmagnetic tunnel junction (MTJ) located in a second level, a pitchdistance between the second pMTJ and the first pMTJ is based upon thereference pitch. A third component can be included in the first memorycell and a fourth component can be included in the second memory cell,wherein the reference pitch is based upon a pitch between the thirdcomponent and fourth component. The memory array can be included amagnoresistive random access memory (MRAM). Respective edges of thefirst pMTJ and second pMTJ can be located with respect to a planeperpendicular to the first and second level. A portion of the first pMTJand a portion of the second pMTJ can overlap each other and the planeperpendicular to the first and second level traverses the overlap. Aportion of the first pMTJ and a portion of the second pMTJ can have aspace between each other, and the plane perpendicular to the first andsecond level and the plane perpendicular to the first and second leveltraverses the space. Respective edges of the first pMTJ and the secondpMTJ can be aligned with the plane perpendicular to the first and secondlevel.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, are included for exemplary illustration of theprinciples of the present invention and not intended to limit thepresent invention to the particular implementations illustrated therein.The drawings are not to scale unless otherwise specifically indicated.

FIG. 1A is a block diagram of an exemplary memory cell configuration inaccordance with one embodiment.

FIG. 1B is a block diagram of another exemplary memory cellconfiguration in accordance with one embodiment.

FIG. 2 is a block diagram comparison of exemplary memory cellconfigurations in accordance with one embodiment.

FIG. 3 is a block diagram of a memory array of pMTJ memory cells inwhich memory pMTJs adjacent to one another in the x and y dimensionsalternate between a first level and a second level.

FIG. 4 is a block diagram of an exemplary memory cell array layoutwithout pMTJ overlap and an exemplary memory cell array layout with pMTJoverlap in accordance with one embodiment.

FIG. 5 is a block diagram top view comparison of two pMTJs that do notoverlap and two pMTJs that do overlap in accordance with one embodiment.

FIG. 6 is a block diagram of another exemplary configuration of aplurality of memory cells in accordance with one embodiment.

FIG. 7 is a block diagram top view of pitch reference componentsincluded in an array in accordance with one embodiment.

FIG. 8 illustrates a magnetic tunnel junction (“MTJ”) in accordance withone embodiment.

FIG. 9 is a flow chart of a fabrication method in accordance with oneembodiment.

FIG. 10 is a flow chart of a fabrication processes in accordance withone embodiment.

FIG. 11 is a flow chart of an exemplary memory fabrication method inaccordance with one embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be obvious toone ordinarily skilled in the art that the present invention may bepracticed without these specific details. In other instances, well knownmethods, procedures, components, and circuits have not been described indetail as not to unnecessarily obscure aspects of the current invention.

Embodiments of the present invention facilitate convenient and efficientincreased memory cell density configuration. In one embodiment, a firstportion of a first memory cell is located in a first layer and a firstportion of a second memory cell is located in a second layer. The firstportion of a first memory cell overlaps the first portion of the secondmemory cell. The first portions of the respective memory cells can beportions of magnetic tunnel junctions (MTJs). In one embodiment, aportion of a MTJ in one memory cell is in one layer of a semiconductordevice and a portion of a MTJ in another memory cell is in anotherlayer, wherein the MTJ portions overlap results in decreased pitchbetween memory cells. The amount of overlap of the MTJs can correspondto a difference between a first minimum lithographic process printinglimitation and a second minimum lithographic process printinglimitation. The first minimum lithographic process printing limitationcan be associated with a MTJ component formation, and the second minimumlithographic process printing limitation can be associated withformation of another component (e.g., a switch, a via, etc.) of therespective memory cells. The other components can be located in a levelthat is different than the levels that include the MTJs.

It is appreciated MTJs can be included in a variety of devices. In oneembodiment, an MTJ is included in magnetoresistive random-access memory(MRAM). The MTJs can have various configurations. In one embodiment, theMTJs can be configured as pillar MTJSs (pMTJs). The pMTJ can beconsidered a 3D MTJ structure.

Various processes can be utilized to fabricate a memory cell. In oneembodiment, a fabrication process utilized to form a portion of a memorycell can have a greater resolution limitation than another fabricationprocess utilized to form another portion of the memory cell. A portionof one memory cell is fabricated in a layer of a semiconductor andoverlaps a portion of another memory cell fabricated in another layer ofthe semiconductor. The difference in resolution limitations can be dueto various aspects of the fabrication processes (e.g., different typesof lithographic processes, different shapes of sub-components beingformed, etc.). In one exemplary implementation, a fabrication process ofa portion of a memory cell has a greater resolution than a fabricationprocess of another portion of a memory cell. Fabrication of asubcomponent of respective memory cells can have greater resolutioncapability than fabrication of another subcomponent of the respectivememory cells, and a subcomponent with lesser resolution in a memory cellcan overlap a subcomponent with lesser resolution in another memorycell. In one embodiment, the portions of sub-components of respectivememory cells that overlap are portions of MTJs and other portions (e.g.transistors, vias, etc.) of the memory cell are formed by fabricationprocesses with greater resolution capabilities than fabrication of theMTJ. It is appreciated the MTJ can be included in a variety of devices.In one embodiment, an MTJ is included in magnetoresistive random-accessmemory (MRAM).

FIG. 1A is a block diagram of an exemplary memory cell configuration100A in accordance with one embodiment. Memory cell configuration 100Aincludes memory cells 110 and 120. Memory cell 110 includes contact 111,pMTJ 112, via 113, and switch 114. Memory cell 120 includes contact 121,pMTJ 122, via 123, and switch 124. The pMTJ 112 is in a different layerthan pMTJ 122 and overlap each other. In one exemplary implementation,the overlap 155 is coordinated with a reference pitch. The referencepitch is associated with a pitch between a first pitch referencecomponent in the memory cell 110 and a second pitch reference componentin the memory cell 120. In one exemplary implementation, the first pitchreference component is switch 114 and the second pitch referencecomponent is switch 124 and the reference pitch is the distance 177 orpitch between switch 114 and switch 124. In one embodiment, byoverlapping the pMTJ 112 and pMTJ 122 in different layers the memorycells can achieve a pitch of 175 from the middle of memory cell 110 tothe middle of memory cell 120.

In one embodiment, the lithographic process utilized to create thereference components allows reference components to have a smaller sizeand pitch than lithographic process limitation utilized to create thepMTJs. Reference components (e.g., switch 114, via 113, etc.) can have asmaller size and pitch than the pMTJs (e.g., 112, etc.) in the x-y plane(e.g., smaller width, length, etc.). In one exemplary implementation,the lithographic process utilized to create the reference components canalso allow the space between reference components in the same level orplane to have smaller spacing than a lithographic process utilized tocreate pMTJs in the same level or plane.

In one embodiment, memory cell configuration 100A includes levels orlayers 10, 20, 30, 40, 50, 60, and 70. Contact 121 is included in level70. The pMTJ 122 is included in level 60. Contact 111 is included inlevel 50. In one exemplary implementation, level 50 is aninterconnection or redistribution layer. The pMTJ 112 is included inlayer 40. The vias 113 and 124 are included in layer 30. The switches114 and 124 are included in layer 20. Layer 10 is a substrate layer. Itis appreciated there can be variations to the component and layerconfigurations. In one exemplary implementation, portions of via 123 arealso included in layers 40, 50, and 60 in addition to layer 30. In oneexemplary implementation, portions of contact 111 are also included inlayers 60 and 70 and extend to be parallel or equal with the top ofcontact 121. It is appreciated that there can be additional layers(e.g., below, above, in between, etc.) of components. Additional layerscan include various components (e.g., pMTJs, vias, switches, lines ortraces, other components, etc.).

It is appreciated the relative location or configuration relationship ofpMTJs in different levels can vary. In one embodiment, the relativelocation of the pMTJs is based upon a differences in location withrespect to a plane perpendicular to the layers or levels. With referenceto FIG. 1, a plane 199 is perpendicular to the layers or levels. In oneembodiment, portions of pMTJs in different levels can overlap each otherwith respect to a plane perpendicular to the levels. In FIG. 1A there isan overlap 155 of the pMTJs 112 and 122. In one exemplaryimplementation, plane 199 is in or traverses the overlap 155. In oneembodiment, the pMTJs in different levels can have a space or gapbetween each other with respect to a plane perpendicular to the levels.

FIG. 1B is a block diagram of another exemplary memory cellconfiguration 100B in accordance with one embodiment. Memory cellconfiguration 100B is similar to memory cell configuration 100A except aportion of pMTJs in different levels have spacing or gap between pMTJsin different levels. Memory cell configuration 100B includes memorycells 130 and 140. Memory cell 130 includes contact 131, pMTJ 132, via133, and switch 134. Memory cell 140 includes contact 141, pMTJ 142, via143, and switch 144. It is appreciated that components of memory cellconfiguration 100B can be included in multiple layers similar to layers10 through 70 and so on. The pMTJ 132 is in a different layer than pMTJ142 but do not overlap each other. In one exemplary implementation, thespacing or gap 157 crossed over a plane 199 perpendicular to the levels.In one exemplary implementation, plane 199 is in or traverses the gap157. In one exemplary implementation, the spacing or gap 157 iscoordinated with or based upon a reference pitch. The reference pitch isassociated with a pitch between a first pitch reference component in thememory cell 130 and a second pitch reference component in the memorycell 140. In one exemplary implementation, the first pitch referencecomponent is switch 134 and second pitch reference component is switch144, and the reference pitch is the distance 178 or pitch between switch134 and switch 144. In one embodiment, by coordinating the spacing orgap 157 between pMTJ 132 and pMTJ 142 in different layers the memorycells can achieve a pitch of 179 from the middle of memory cell 130 tothe middle of memory cell 140.

In one embodiment, an edge in respective pMTJs in different levels canalign with one another in a plane perpendicular to the levels. In oneembodiment, there is not an overlap or spacing between planes of arespective edge of pMTJs in different levels. In one exemplaryimplementation, there is no overlap (e.g., distance 155 in FIG. 1A is 0)and no space (e.g., distance 157 in FIG. 1B is 0) between respectiveedges of pMTJs in different levels.

In one embodiment, respective edges of the first pMTJ and second pMTJare located with respect to a plane perpendicular to the first andsecond level. A portion of the first pMTJ and a portion of the secondpMTJ can overlap each other and the plane perpendicular to the first andsecond level traverses the overlap. A portion of the first pMTJ and aportion of the second pMTJ can have a space between each other, and theplane perpendicular to the first and second level traverses the space.The respective edges of the first pMTJ and the second pMTJ can bealigned with the plane perpendicular to the first and second level. Inone exemplary implementation, the respective edges are the edges of thepMTJ closest to the plane perpendicular to the levels. The respectiveedges can be edges of pMTJs closest to a plane similar to plane 199.

In one embodiment, a pitch between memory cells with pMTJs in differentlevels can be smaller than a pitch between memory cells with pMTJs inthe same level. FIG. 2 is a block diagram of exemplary comparison ofmemory cell configurations in accordance with one embodiment. Memorycell 210 includes contact 211, pMTJ 212, via 213 and switch 214. Memorycell 220 includes contact 221, pMTJ 222, via 223 and switch 224. Memorycell 230 includes contact 231, pMTJ 232, via 233 and switch 234. Memorycell 240 includes contact 241, pMTJ 242, via 243 and switch 244. ThepMTJs 212 and 222 are in different layers from one another while thepMTJs 232 and 242 are in the same level as one another. By overlappingthe pMTJs 212 and 222 in different levels, the pitch 251 between memorycells 210 and 220 is less or smaller than the memory cell pitch 252between memory cells 230 and 240.

In one embodiment, the pMTJs are included in a MRAM. The pMTJs arecoupled to selector switches that are utilized to select or not selectthe memory cell during various operations (e.g., read, write, erase,etc.). In one exemplary implementation, adjacent switches (in the X andY directions) are connected to a pMTJ in a different level from oneanother and portions of the pMTJs can overlap. The resulting reducedmemory cell pitch size enables increased memory cell density and higherinformation or bits/area capacity for an MRAM chip.

It is appreciated there can be multiple memory cells configured inmemory cell arrays. In one embodiment, when viewed in the projection ofFIG. 3 which includes multiple planes, pMTJs adjacent to one another inthe x and y dimensions (e.g., length and width) are in different levels.In one exemplary implementation, adjacent memory pMTJs alternate levels.FIG. 3 is a block diagram of a memory array of pMTJ memory cells (e.g.,311, 321,312, etc.) in accordance with one embodiment. The pMTJsadjacent to one another in the x and y dimensions alternate between afirst level 1 and second level 2. For example, pMTJ memory cell 311 isin level 2 and pMTJ memory cells 321 and 312 are in level 1.

FIG. 4 is a block diagram of an exemplary memory cell array 410 layoutwithout pMTJ overlap and an exemplary memory cell array 420 layout withpMTJ overlap in accordance with one embodiment. Memory cell array 410includes a plurality of memory cells (e.g., memory cells 411, 412, 414,415, etc). The layout illustrates the pitch size 488 as defined bylithography limitations. The solid circular lines (e.g., 477, 497, etc.)outlining the memory cells or dots represent the dot size afterlithography. The figure also shows the size of the dots or memory cellsafter trimming. The broken circular lines (e.g., 478, 498, etc.) in thememory cells or dots represent the dot or pMTJ size after trimming.Memory cell array 420 includes a plurality of memory cells (e.g., memorycells 421, 422, 423, 425, etc). The layout illustrates the pitch size489 is not tied to lithography limitations associated with the pMTJ. Inone embodiment, the pitch size 489 corresponds to pitch limitations ofcomponents other than the pMTJ.

In one embodiment without overlap, the pitch size of the memory cellsremains relatively constant or the same even though components orstructures formed by an initial photo resist processes are trimmedsignificantly. FIG. 5 is a block diagram top view of two pMTJs 570 and580 that do not overlap and two pMTJs 510 and 520 that overlap inaccordance with one embodiment. The solid line 571 indicates thelithographic printing or formation boundaries of a pMTJ 570 in afabrication level and the solid line 581 indicates the lithographicprinting or formation boundaries of pMTJ 580 in the same fabricationlevel. The dashed line 572 indicates the trimming boundaries of pMTJ 510and dashed line 582 indicates the trimming boundaries of pMTJ 520. Thepitch 592 between pMTJ 570 and pMTJ 580 is determined by the pMTJlithographic formation limitations or resolution 595 and the spacinglimitation 597. The spacing limitation 597 can be influenced or adjustedto compensate for various factors (e.g., minimum spacing lithographicformation limitations, capacitance considerations, electricalinterference, etc.).

The solid line 511 indicates the lithographic printing or formationboundaries of pMTJ 510 in one fabrication level and the solid line 531indicates the lithographic printing or formation boundaries of pMTJ 530in another fabrication level. The dashed line 512 indicates the trimmingboundaries of pMTJ 510 in the first level and the dashed line 532indicates the trimming boundaries of pMTJ 530 in the second level. ThepMTJ 510 and pMTJ 530 still include an overlap 552 after trimming. Thepitch 591 is smaller than pitch 592 as the pMTJs 510 and 530 associatedwith pitch 591 have an overlap and the pMTJs 570 and 580 associated withpitch 592 do not overlap.

In one embodiment, placement of a pMTJ can be configured based uponconsiderations or coordination associated with multiple pitch referencecomponents. In one exemplary implementation, the placement of a pMTJ isconfigured based upon a lithographic limitation associated withformation of a switch and a lithographic limitation associated with theformation of a via. With reference back to FIG. 2, the placement of apMTJ 232 can be configured based upon a lithographic limitationassociated with formation of switches 234, 224, and 244 and alithographic limitation associated with the formation of vias 223 and243. For example, the placement of via 243 with respect to an edge ofswitch 244 may limit the placement of the pMTJ 232. If via 243 islimited to a location closer to the middle of the switch 244, this maylimit the ability of pMTJ 232 to shift and thus may limit the overlapand resulting pitch.

It is appreciated that configurations of pMTJ overlapping can vary. FIG.6 is a block diagram of an exemplary memory cell array configuration 600in accordance with one embodiment. Memory cell configuration 600includes memory cells 610, 620, 630, and 640. Memory cell 610 includescontact 611, pMTJ 612, via 613, and switch 614. Memory cell 620 includescontact 621, pMTJ 622, via 623, and switch 624. Memory cell 630 includescontact 631, pMTJ 632, via 633, and switch 634. Memory cell 640 includescontact 641, pMTJ 642, via 643, and switch 644. The pMTJs 612 and 632are in different layers than pMTJ 622 and 642. By overlapping the pMTJsin different levels, the pitch cell between memory cells 610, 620, 630,and 640 can be maintained based upon a reference pitch. A pMTJ on onelevel can overlap multiple pMTJs on another level. For example, pMTJ 622in the second level overlaps pMTJs 612 and 632 in the first level, andpMTJs 622 and 642 in the second level overlap pMTJs 632.

It is appreciated pitch reference component sizes may vary. In oneembodiment, the locations of respective pMTJs in different levels andcorresponding overlaps are coordinated to accommodate differences inpitch reference component sizes. FIG. 7 is a block diagram top view ofpitch reference components included in an array in accordance with oneembodiment. The pitch reference components include 711,712, 713, 721,722, 723, 731, 732, and 733. In one embodiment, the pitch referencecomponents can have different shapes (e.g., square, rectangular,circular, etc.). In one exemplary implementation, pitch referencecomponent 731 has a width of 2f in the x direction and a length of 3f inthe y direction, where f is the minimum lithographic process distance orresolution available for the device fabrication. The minimumlithographic process distance or resolution available for the devicefabrication can correspond to a line or trace width.

FIG. 8 illustrates a magnetic tunnel junction (“MTJ”) 800 in accordancewith one embodiment. MTJ 800 includes one or more seed layers 810provided at the bottom of stack 800 to initiate a desired crystallinegrowth in the above-deposited layers. An antiferromagnetic layer 812 isdisposed over seed layers 810. MTJ 830 is deposited on top of syntheticantiferromagnetic (SAF) layer 820. MTJ 830 includes reference layer 832,which is a magnetic layer, a non-magnetic tunneling barrier layer (i.e.,the insulator) 834, and the free layer 836, which is also a magneticlayer. It should be understood that reference layer 832 can actually bepart of SAF layer 820, but forms one of the ferromagnetic plates of MTJ830 when the non-magnetic tunneling barrier layer 834 and free layer 836are formed on reference layer 832. As shown in FIG. 8, magneticreference layer 832 has a magnetization direction perpendicular to itsplane. As also illustrated in FIG. 8, free layer 836 also has amagnetization direction perpendicular to its plane, but its directioncan vary by 180 degrees.

The first magnetic layer 814 is disposed over seed layer 810. SAF layer820 also has an antiferromagnetic coupling layer 816 disposed over thefirst magnetic layer 814. Furthermore, a nonmagnetic spacer 840 isdisposed on top of MTJ 830 and a polarizer 850 is disposed on top of thenonmagnetic spacer 840. Polarizer 850 is a magnetic layer that has amagnetic direction that may be parallel to its plane and orthogonal tothe magnetic direction of the reference layer 832 and free layer 836.Polarizer 850 is provided to polarize a current of electrons(“spin-aligned electrons”) applied to MTJ structure 830. A capping layer860 can be provided on top of perpendicular polarizer 850 to protect thelayers below on MTJ stack 800. Finally, a hard mask 870 is depositedover capping layers 860 and is provided to pattern the underlying layersof the MTJ structure 800, using a reactive ion etch (RIE) and ion beametch processes. In one embodiment, the MTJ structure is similar toportions of a pMTJ (e.g., pMTJ 112, 122, 132, 142, 612, 622, 421, 422,etc.)

FIG. 9 is a flow chart of an exemplary fabrication method in accordancewith one embodiment.

In block 910, switch structures are formed. In one embodiment, theswitches are transistors. The transistors can be a complimentary metaloxide silicon (CMOS) transistors. In one exemplary implementation, aswitch is configured to selectively operate a memory cell during variousactivities (e.g., read, write, erase, etc.).

In block 920, conductor vias are formed. The conductor vias are coupledto the switches. In one embodiment, formation of the conductor viasinclude, leveling or smoothing off (e.g., CMP, etc.) the top of thevias, depositing an insulation layer (e.g., oxide, etc.), etching a viaspace in the insulation layer, and filling the space in with a viaconductor (e.g., metal, etc.).

In block 930, MTJ structures or components are formed. One group of MTJstructures are formed in one layer of the semiconductor and anothergroup of MTJ structures is form in another layer. The location ofportions of the MTJ structure formed in one layer and portions of theMTJ structure formed in the other layer can be coordinated based upon areference pitch. Portions of the MTJ structure formed in one layer canoverlap portions of the MTJ structure formed in the other layer. The MTJstructures are coupled to the vias. In one embodiment, the MTJstructures are coupled to the vias in an alternating pattern so thatgroups of MTJs from different layers are coupled to every other switchstructure respectively in an X and Y planar direction. In oneembodiment, the MTJs are formed in a circular or pillar configuration.In one exemplary implementation, the formation of the MTJs can includemagnetic material deposition (pMTJ), hard mask deposition, pMTJannealing, photolithography for pillar definition, reactive ion retchingof hard mask, ion beam etching of the pMTJ to form pillars, insulatordeposition and smoothing the surface with CMP (chemical mechanicalpolishing) for the next level of pMTJ formation and so on.

In block 940, contacts are formed. The contacts are coupled to the MTJs.

It is appreciated that multiple layers of MTJs can be fabricated. It isappreciated, there can be more than 2 layers or levels (e.g., 3, 4, 5,etc.) than include MTJs, pMTJs, and so on. Again, it is appreciated MTJsin different levels can be configured or located based upon a referencepitch. MTJs in different levels can include overlapping portions. It isappreciated other components of the memory cell (e.g., switches,transistors, vias, contacts, traces, etc.) can be included in multiplelevels. The components (e.g., switches, transistors, vias, contacts.traces, etc.) can be configured or located based upon a reference pitch.Components in different levels can include overlapping portions. In oneembodiment, similar lithographic mask patterns are utilized to formdifferent layers of MTJs. In one exemplary implementation, similarlithographic masks utilized to form layers in which MTJs overlap, exceptthe respective lithographic masks include an offset in the patterns ofanother and the offset corresponds to the overlap. The MTJ fabricationin multiple layers can include multiple anneal processes. In oneexemplary implementation, the number of MTJ layers is coordinated andbalanced with impacts associated with the annealing processes.

Various processes can be utilized to fabricate a memory cell. In oneembodiment, a fabrication process utilized to form a portion of a memorycell can have a greater resolution limitation than another fabricationprocess utilized to form another portion of the memory cell.

FIG. 10 is a flow chart of exemplary fabrication processes in accordancewith one embodiment.

In block 1010, a portion of one memory cell is fabricated in a layer ofa semiconductor. The portion is fabricated using one fabrication processthat has a first set of fabrication limitations. The set of limitationscan be resolution limitations. The set of limitations can correspond tothe type of fabrication process. The fabrication process can be alithographic process. The lithographic process can include an ion beametch process, a plasma etch process, a reactive etch process, and so on.In one embodiment, the portion of the memory cell can be a subcomponent.The memory cell subcomponent can be a switch, via, and so on. In oneexemplary implementation, the portion overlaps a portion of anothermemory cell. The portion can be in a different layer as the portion ofthe of the other memory cell. In one exemplary implementation, theportion does not overlap a portion of another memory cell. The portioncan be in the same layer as the portion of the of the other memory cell.The overlapped portion of the other memory cell is in a different layer.

In block 1020, another portion of the memory cell is fabricated. Theother portion is fabricated using a fabrication process that has asecond set of fabrication limitations. The second set of fabricationslimitations can include different resolution limitations than the firstset of fabrication limitations. The set of limitations can correspond tothe type of fabrication process. The fabrication process can be alithographic process. The lithographic process can include an ion beametch process, a plasma etch process, a reactive etch process, and so on.In one embodiment, the portion of the memory cell can be a subcomponent.The memory cell subcomponent can be a pMTJ. The portion can befabricated to overlap a portion of another memory cell. The overlappedportion of the other memory cell is in a different layer.

FIG. 11 is a flow chart of memory fabrication method 1100 in accordancewith one embodiment. In one exemplary implementation, the location of asecond pMTJ and a first pMTJ with respect to one another is coordinatedbased upon a reference pitch distance. The reference pitch distance canbe based upon a pitch between a first pitch reference component and asecond pitch reference component. In one embodiment, lithographicprinting capabilities with respect to the first pitch referencecomponent and the second pitch reference component is used to set ordetermine the reference pitch.

In block 1110, a first pitch reference component is formed. The firstpitch reference component can be a switch. The reference component sizecan be based upon a minimum lithographic processing dimension. Thereference component size can be reduced and based upon a minimumtrimming processing dimension.

In block 1120, a second pitch reference component is formed. The secondpitch reference component can be a switch. The reference component sizecan be based upon a minimum lithographic processing dimension.

In block 1130, a first pillar magnetic tunnel junction (pMTJ) located ina first level in a semiconductor device is formed using a first runlithographic process. The first pitch reference component is coupled tothe first pMTJ.

In block 1140, a second pillar magnetic tunnel junction (pMTJ) locatedin a second level in the semiconductor device if formed using a secondrun lithographic process. The second pitch reference component iscoupled to the second pMTJ.

In one embodiment, the location of the second pMTJ with respect to thefirst pMTJ is coordinated to comply with a reference pitch for memorycells. The location of the second pMTJ and the second pMTJ with respectto each other and a plane perpendicular to the first level and thesecond level can be coordinated to comply with a reference pitch for thememory cells. A portion of the second MTJ can overlap a portion of thefirst MTJ and the plane perpendicular to the first level and the secondlevel traverses the overlap. There can be a space between the second MTJand the first MTJ, and the plane perpendicular to the first level andthe second level traverses the space. Respective edges of the second MTJand the first MTJ are aligned along the plane perpendicular to the firstlevel and the second level. The MTJs can be included in a pillarconfiguration and included in pMTJs.

In one embodiment, a portion of the second pMTJ overlaps a portion ofthe first pMTJ wherein the overlap corresponds to an offset in patterndifference between the first level and the second level. A firstlithographic mask can be utilized to form the first pMTJ and a secondlithographic mask can be utilized to form the second pMTJ, whereinlithographic patterns for forming the first pMTJ and second pMTJ are thesame except they are offset from one another to correspond to theoverlap.

In one embodiment, a minimum lithographic processing dimensionassociated with the first pitch reference component and the second pitchreference component is less than a minimum/lithographic processingdimension associated with the first pMTJ and the second pMTJ. Thefabrication processes utilized to form the first pitch referencecomponent and the second pitch reference have a greater resolution thanfabrication processes utilized to form the first pMTJ and second pMTJ.The smallest dimension can correspond to a conductive line trace. ThepMTJs can be formed using a hard mask and ion beam etch. The first pMTJand the second pMTJ can also be trimmed. In one embodiment, the memorycells are included in memory cell array of a memory device. The memorydevice can be a magnoresistive random access memory (MRAM).

Embodiments of the present invention can facilitate efficient andeffective memory cell density configuration. In one embodiment, MTJcomponents of a memory cell are configured in different levels and thepitch between the MTJ components of between memory cells can be adjustedor based upon a reference pitch. The reference pitch can correspond tocomponents formed by processes that facilitate relatively tight or closepitches. In one exemplary implementation, the reference pitch can benarrower than pitches otherwise associated with traditional magneticmemory cell formation. The closer or tighter pitches can enableincreased memory cell density. The increased memory cell density in turncan enable greater information storage per device area.

Some portions of the detailed descriptions are presented in terms ofprocedures, logic blocks, processing, and other symbolic representationsof operations on data bits within a computer memory. These descriptionsand representations are the means generally used by those skilled indata processing arts to effectively convey the substance of their workto others skilled in the art. A procedure, logic block, process, etc.,is here, and generally, conceived to be a self-consistent sequence ofsteps or instructions leading to a desired result. The steps includephysical manipulations of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical, magnetic,optical, or quantum signals capable of being stored, transferred,combined, compared, and otherwise manipulated in a computer system. Ithas proven convenient at times, principally for reasons of common usage,to refer to these signals as bits, values, elements, symbols,characters, terms, numbers, or the like.

The terms “first,” “second,” “third,” “fourth,” and the like in thedescription and in the claims, if any, are used for distinguishingbetween similar elements and not necessarily for describing a particularsequential or chronological order. It is to be understood that any termsso used are interchangeable under appropriate circumstances such thatthe embodiments described herein are, for example, capable of operationin sequences other than those illustrated or otherwise described herein.Similarly, if a method is described herein as comprising a series ofsteps, the order of such steps as presented herein is not necessarilythe only order in which such steps may be performed, and certain of thestated steps may possibly be omitted and/or certain other steps notdescribed herein may possibly be added to the method.

It should be borne in mind, however, that all of these and similar termsare associated with the appropriate physical quantities and are merelyconvenient labels applied to these quantities. Unless specificallystated otherwise as apparent from the following discussions, it isappreciated that throughout the present application, discussionsutilizing terms such as “processing”, “computing”, “calculating”,“determining”, “displaying” or the like, refer to the action andprocesses of a computer system, or similar processing device (e.g., anelectrical, optical, or quantum, computing device) , that manipulatesand transforms data represented as physical (e.g., electronic)quantities. The terms refer to actions and processes of the processingdevices that manipulate or transform physical quantities within acomputer system's component (e.g., registers, memories, other suchinformation storage, transmission or display devices, etc.) into otherdata similarly represented as physical quantities within othercomponents.

It is appreciated that embodiments of the present invention can becompatible and implemented with a variety of different types of tangiblememory or storage (e.g., RAM, DRAM, flash, hard drive, CD, DVD, etc.).The memory or storage, while able to be changed or rewritten, can beconsidered a non-transitory storage medium. By indicating anon-transitory storage medium it is not intend to limit characteristicsof the medium, and can include a variety of storage mediums (e.g.,programmable, erasable, nonprogrammable, read/write, read only, etc.)and “non-transitory” computer-readable media comprises allcomputer-readable media, with the sole exception being a transitory,propagating signal.

It is appreciated that the specification includes a listing of exemplaryconcepts or embodiments associated with the novel approach. It is alsoappreciated that the listing is not exhaustive and does not necessarilyinclude all possible implementation. The concepts and embodiments can beimplemented in hardware. In one embodiment, the methods or processdescribe operations performed by various processing components or units.In one exemplary implementation, instructions, or directions associatedwith the methods, processes, operations etc. can be stored in a memoryand cause a processor to implement the operations, functions, actions,etc.

It is appreciated that a memory storage management systems and methodscan include the exemplary concepts or embodiments. It is alsoappreciated that the listing is not exhaustive and does not necessarilyinclude all possible implementations. The concepts and embodiments canbe implemented in hardware, firmware, software, and so on. In oneembodiment, the following concepts include methods or processes thatdescribe operations performed by various processing components or units.In one exemplary implementation, instructions or directions associatedwith the methods, processes, operations etc. can be stored in a memoryand cause a processor to implement the operations, functions, actions,etc.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents. The listing of steps within method claims do not imply anyparticular order to performing the steps, unless explicitly stated inthe claim.

What is claimed is:
 1. A method comprising: forming a first pitchreference component; forming a second pitch reference component; forminga first pillar magnetic tunnel junction (pMTJ) located in a first levelin the semiconductor device using a first run lithographic process; andforming a second pillar magnetic tunnel junction (pMTJ) located in asecond level in the semiconductor device using a second run lithographicprocess; wherein the location of the second pMTJ with respect to thefirst pMTJ is coordinated based upon a reference pitch distance betweenthe first pitch reference component and first pitch reference component.2. The method of claim 1, wherein the first pitch reference component isa first switch coupled to the first pMTJ and the second pitch referencecomponent is a second switch coupled to the second pMTJ.
 3. The methodof claim 2, wherein the first reference component is a first switch andthe second reference component is a second switches.
 4. The method ofclaim 1, wherein the reference component size is based upon a minimumlithographic processing dimension.
 5. The method of claim 1, wherein thereference component size is based upon a minimum trimming processingdimension.
 6. The method of claim 1, wherein a minimum lithographicprocessing dimension associated with the first pitch reference componentand the second pitch reference component is less than a minimumlithographic processing dimension associated with the first pMTJ and thesecond pMTJ.
 7. The method of claim 1, wherein the smallest dimensioncorresponds to a conductive line trace.
 8. The method of claim 1,wherein the pMTJs are formed using a hard mask and ion beam etch.
 9. Themethod of claim 1, wherein the first pMTJ and the second pMTJ overlapeach other.
 10. A method comprising: forming a first pillar magnetictunnel junction (pMTJ) located in a first level in the semiconductordevice, wherein the first pMTJ is associated with a first memory cell;and forming a second pillar magnetic tunnel junction (pMTJ) located in asecond level in the semiconductor device, wherein the second pMTJ isassociated with a second memory cell; wherein the location of the secondpMTJ with respect to the first pMTJ is coordinated based upon areference pitch distance.
 11. The method of claim 10, furthercomprising; forming a first pitch reference component, wherein the firstpitch reference component is associated with the pMTJ memory cell, andforming a second pitch reference component, wherein the second pitchreference component is associated with the second pMTJ memory cell,wherein a pitch between the first pitch reference component and thesecond pitch reference component is used to determine the referencepitch.
 12. The method of claim 11, wherein fabrication processesutilized to form the first pitch reference component and the secondpitch reference have a greater resolution than fabrication processesutilized to form the first pMTJ and second pMTJ.
 13. The method of claim10, wherein a portion of the second pMTJ overlaps a portion of the firstpMTJ and the overlap is coordinated to comply with a reference pitchassociated with other components ,and an offset in pattern differencebetween the first level and the second level corresponds to the offset.14. The method of claim 10, wherein a first lithographic mask isutilized to form the first pMTJ and a second lithographic mask isutilized to form the second pMTJ, wherein lithographic patterns forforming the first pMTJ and second pMTJ are the same except they areoffset from one another to correspond to the overlap.
 15. The method ofclaim 10, wherein the lithographic printing capabilities with respect tothe first pitch reference component and the second pitch referencecomponent is used to set the reference pitch.
 16. The method of claim10, wherein the first pitch reference component is a first switchcoupled to the first pMTJ and the second pitch reference component is asecond switch coupled to the second pMTJ.
 17. A method of forming amemory cell array in a memory device, the method comprising: forming afirst memory cell with a first magnetic tunnel junction (MTJ) located ina first level; and forming a second memory cell with a second magnetictunnel junction (MTJ) located in a second level, wherein a pitch betweenthe second pMTJ and first pMTJ is based upon a reference pitch.
 18. Themethod of claim 17, wherein a third component is included in the firstmemory cell and a fourth component is included in the second memorycell, wherein the reference pitch is based upon a pitch between thethird component and fourth component.
 19. The method of claim 17,wherein respective edges of the first pMTJ and second pMTJ are locatedwith respect to a plane perpendicular to the first and second level. 20.The method of claim 19, wherein a portion of the first pMTJ and aportion of the second pMTJ overlap each other and the planeperpendicular to the first and second level traverses the overlap. 21.The method of claim 19, wherein a portion of the first pMTJ and aportion of the second pMTJ have a space between each other and the planeperpendicular to the first and second level, and the plane perpendicularto the first and second level traverses the space.
 22. The method ofclaim 19, wherein respective edges of the first pMTJ and the second pMTJare aligned with the plane perpendicular to the first and second level.23. A method of claim 17 wherein the memory device is a magnoresistiverandom access memory (MRAM).